The present invention relates to novel heavy duty softergent liquid compositions comprising at least 10% nonionic surfactant, and preferably about 6-9% of higher alkyl dimethyl 2-ethyl hexyl quaternary softening compound in conjunction with about 0.1-1% of an anionic optical brightener, to improve low temperature product stability and softening properties. It is preferable to add an anionic surfactant in the molar ratio of 1:1 anionic surfactant:cationic softening compound, and about 4-8% by weight of a lower mono- or di-hydric alcohol.
The use of cationic quaternary ammonium compounds as softeners for textile products is very well known in the art. It is also well known to employ such materials for their softening effects during the laundering operation and particularly in the rinse cycle of the laundering process. This latter technique has been necessitated by the fact that the aforesaid quaternary compounds heretofore employed, being mainly cationic in nature, form a complex with the anionic detergent, one of the major types of detergents used in the washing cycle. However, the use of the quaternary softening agent in the rinse cycle is burdensome to the consumer. Consequently, detergents have been combined with the compatible fabric softeners for use in the wash cycle of the laundering operation.
It is also known that the cationic softening compounds interfere with the brightening activity as well as the cleaning efficiency of the detergent. As a result, the prior art has used nonionic surfactants in order to overcome this interference with brightening activity and cleaning efficacy, as shown in U.S. Pat. Nos. 4,264,457; 4,239,659; 4,259,217, 4,222,905, etc.
Another problem associated with the presence of said cationic agents in liquid softergent compositions containing anionic optical brightener is product instability, particularly at low temperatures (about 40.degree. F.), due to the tendency of the quaternary compounds to form a complex with the optical brightener which does not resolubilize in the aqueous media.
U.S. Pat. No. 4,134,838 discloses a fabric conditioning composition comprising a softening agent which include prior art cationic quaternary ammonium compounds such as di-tallow dimethyl ammonium chloride and trimethyl tallow ammonium chloride, and a deodorant perfume to which may be added water soluble detergent actives well known in the art such as anionic, nonionic, etc.; inorganic or organic detergent builders; optical brighteners; oils and fragrances; antistatic agents; germicides; bodying agents; soil release agents; ironing aids; bleaches; enzymes; etc. The conditioning compound may be in the form of a solid or liquid composition. The illustrated aqueous liquid fabric conditioning compositions contain a maximum of 6% by weight of the cationic softening agent (Example 1).
U.S. Pat. No. 4,341,644 discloses a textile softener composition comprising a quaternary ammonium salt mixture dispersed in an aqueous medium where the 4 radicals contain a total of 40-75% saturated aliphatic straight chains, 5-45% unsaturated aliphatic chains and 3-55% branched aliphatic chains.
European Patent No. 0,074,056 discloses a liquid softening/rinsing agent for laundry consisting of an aqueous solution or dispersion of a quaternary ammonium compound, wherein two of the radicals are methyl-branched alkyl or alkenyl radicals having 12-30 carbons, and the other two radicals are C1-C4 alkyl groups.
U.S. Pat. Nos. 4,569,800 and 4,675,118 discloses a fabric softening composition comprising a quaternary ammonium compound, wherein one radical is a higher aliphatic radical, another radical is 2-ethyl hexyl, and the remaining two radicals are methyl radicals, dissolved in ethanol, water, isopropyl alcohol and blends thereof.
However, none of the cited prior art references disclose a stable heavy duty liquid softergent composition for simultaneously cleaning and softening fabrics comprising a higher alkyl 2-ethyl hexyl dimethyl quaternary ammonium compound as the softening agent, an anionic optical brightener, at least 10% nonionic surfactant dissolved in an aqueous medium.